Hey there Turbine - I've not been following too closely but you are treading along a path that many of us have walked before you.
Don't be too hard on yourself. You are dealing with things that are life-altering and largely out of your hands.
Don't expect anything much from her either the practical nor the emotional. Superficially you appear to be around where I was in June 2016 when I was whacked with so many 2X4s that I eventually built myself a virtual "Cabin in the Woods".
You've heard this a bucket of times already I am sure but I'll repeat it. Focus on yourself and your own journey. Be the "sane parent" for your kids and grandkids. They are going to be confused and need you to be their lighthouse on the rock.
Without detailed reading, it would appear that in some ways your story is similar to mine - heck pretty much all the stories here are the same in some way or another. Know that this isn't about you. Also know that at this point that there's not a darned thing you can do that will change her mind or swerve her from her course.
I'm sorry if that isn't something you are ready to hear at this point and yes - I could well be wrong.
As far as your wife goes, she isn't someone who can be trusted. She's probably up way past the eyeballs in lies and secrets, most of which you probably don't want to know. She's also, like so many, unlikely to do any of the adulting or heavy-lifting. She is being very very selfish right now.
Is she going through a MLC or whatnot? Difficult to say and irrelevant. You can't help her and she doesn't want your help. Will she come out the other side and look for you? Again, difficult to say and also still irrelevant. Many of us put our lives on hold waiting. Some for longer durations than others.
Good luck. This stuff is hard.
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells